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Finding the Fourth Proportional to 71.80, 99.09 and 39.05

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Solution

The fourth proportional to 71.80, 99.09 and 39.05 is: 53.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.80 : 99.09 = 39.05 : x
  2. Step 2: Convert to fraction form
    71.80/99.09 = 39.05/x
  3. Step 3: Cross multiply
    71.80x = 99.09 × 39.05
  4. Step 4: Simplify right side
    71.80x = 3,869.82
  5. Step 5: Solve for x
    x = 3,869.82/71.80
  6. Step 6: Final answer
    x = 53.90

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.